In the prior art, cyclone separators are used for separation of particles of solid matter present in gas flows. In a cyclone separator, the gaseous medium flow enters inside the cyclone separator into a centrifugal flow which revolves inside the cyclone, as a rule, flowing from the top towards the bottom. When the cyclone operates in the vertical position, the inlet of the gaseous medium flow is placed at the top edge of the cyclone separator, in which case the gaseous medium flow that flows in starts revolving downwards inside the cylindrical cyclone separator. When the revolving medium flow flows down into the conical bottom portion of the cyclone separator while maintaining its flow velocity, the revolving medium flow is accelerated at a certain angular velocity. When the revolving medium flow reaches the bottom of the conical bottom portion of the cyclone separator, the revolving medium flow is forced to turn upwards while maintaining its sense of rotation. Then, as is well known, at the lowest point in the bottom end of the cyclone separator, a so-called tornado effect is produced, which is seen, for example, in summer in wind whirls.
Frequently, dust and other solid matter is absorbed into such tornado whirls, being carried along by the tornado whirl and raised even to a high altitude. It is only after disintegration of the tornado whirl that the solid matter can fall down freely and be separated from the tornado to the environment.
In principle, the same also takes place in a cyclone separator regarding the tornado formed inside the conical part at the lower end. The tornado vortex always carries along with it some of the dust or particles of solid matter entering into the cyclone along with the gaseous medium flow. This is why cyclone separators can, as a rule, not be considered to be very good dust separators, because, along with the tornado flow, even large dust particles can flow out of a cyclone separator, for which reason, by means of the prior-art cyclone separators, a particularly precise separation limit cannot be achieved.
At present, a number of different cyclone solutions are used, of which so-called low-pressure, medium-pressure, and high-pressure cyclones should be mentioned. This refers to the pressure loss in the gaseous medium flowing in the cyclone separator that is required by the flowing-through with a nominal volume. Low-pressure cyclones usually have rather large diameters. On the other hand, the diameters of high-pressure cyclones are relatively small. In high-pressure cyclones, the pressure loss may be up to 2000 Pa, whereas in low-pressure cyclones the pressure loss is usually less than 1000 Pa. High-pressure cyclones are often constructed side by side as groups, in which case such a solution is called a multi-cyclone battery. Such a multi-cyclone battery is relatively difficult to manufacture, because it comprises a number of small cyclones, whose dimensional accuracy must be very high. This is why the manufacture of multi-cyclone batteries is relatively expensive. Also, owing to the magnitude of the pressure loss, their operation requires considerably more energy than the operation of low-pressure cyclones does.
The efficiency of separation of cyclone separators depends on the centrifugal field formed inside the cyclone separator. It is commonly known that the higher the angular velocity of the gaseous medium flow, the more intensive is the centrifugal field, and that the intensity of the centrifugal field is directly proportional to the second power of the angular velocity of the medium flow. This is why small-diameter cyclone separators are more efficient separators than cyclone separators of larger diameter. It also comes from this that, in practical solutions, multi-cyclones are adopted more and more frequently even though their investment cost and power consumption are higher. In spite of this, cyclone separators are not capable of meeting the requirements of good efficiency of separation.
From the prior art, a solution is known by whose means the tornado effect can be eliminated to a reasonable extent. This solution consists of a tornado elimination plate placed at a suitable distance from the orifice of the centre pipe of the cyclone separator, which plate prevents direct flow of the tornado flow into the centre pipe. A drawback of this prior-art solution is intensive wear of the elimination plate, and further, the size of the elimination plate may produce undue wear of the cylinder part of the cyclone separator.